Switching device



1927' J. J. KUHN ET AL.

SWITCHING DEVICE Filed Dec. 24, 1925 r r. 0 if 5 0 W Patented Oct. 11, 1927.

UNITED STATES FFICE.

JOHN J. KUHN, OF ELIZABETH, NEW JERSEY, AND WALTER L. BETTS, OF BROOKLYN,

NEW YORK, ASSIGNORS T WESTERN ELECTRIC COMPANY, INCORPORATED, 0F 7 NEW YORK, N. Y., A CORPORATION OF NEW YORK. i

SWITCHING DEVICE.

This invention relates to switching devices and more specifically to a type of switching device particularlywell adapted for use for controlling the volume in. a radio amplifier circuit and the like.

The object of this invention is to provide a switching device and circuit arrangement whereby the volume of input energy inv a radio amplifier circuit may be controlled in a simple and positive manner.

A feature of the invention is the provision of a switching device having a set of connected resistances, a cam being provided on the shaft which when the brush leaves the last resistance element shifts a set of contacts to connect an additional por tio of the secondary winding of the input coil to the grid circuit to change the gain, the said resistances being connected in multiple to a second set of terminals over which the brush sweeps in the other half of its movement.

Other features and advantages will appear from the following description and by the claims appended thereto, reference Y being had to the accompanying drawing in which the reference letter CA indicates an amplifier circuit arrangement and SD a switching device .constructedaccording to the features of this invention.

In its preferred form the switch comprises a knob 10 adapted to be manually operated for moving a'switch wi en 11 in contacting relation with sets 0 contact members such as'12, 13, 14, and 12, 13, 14' etc., which are preferably mounted in an arcuated row on a suitable panel not shown. Contacts 12, 13 and 14 are connected to tapped off portions of potentiometer P, each contact 13, 14, etc.being multipled in a consecutive order to contacts 13', 14', etc.

The knob 10 and wiper 11 are securely mounted on a shaft 15 which carries a cam 16, disposed in operable relation with the free end portion of a resilient contact operating member 17. The position of cam 16, with respect to wiper 11 and the contact menibers 12, 13, 14 and 12', 13, 14 etc., is such that when the wiper 11 is moved from contact 12' in a counter clock-wise direction, the cam 16 engages the contact operating member 17 for breaking the contact between springs 18 and 20 and simultaneously closing the contact between springs 21 and 20,

the spring 20 being brought in'contacting relation with the cont-act spring 21, through the medium of its own tension. 7

These contact springs form parts of the ampllfier circuit adapted for operating a telephone receiver TR which may be of the loud speaker sort used in public address or similar system. As shown in the drawing this amplifier circuit may comprise a vacuum tube repeater 25 constituting the first stage of amplification and the vacuum tube 26, the second stage of amplification. The filament current for the tubes 25 and 26 is supplied by batteries 32 and 33 respectivelv. The tubes 25 and 26 are each illustrated as three element tubeelectron discharge de vice. Each comprises an anode, a cathode, and a control electrode. The grid or control electrodeof tube 25 is connected to the incoming line 28 by a transformer 27 having a primary and secondary winding. The grid of tube 26 is connected to contacts 12, 13, 14, etc. and resistances 35, 36, etc. of

the switching device through wiper 11, thus providing means for controlling. the voltage impressed on the grid of tube 26 from the plate of tube 25. The leads 29 tapped off from a portion of the secondary of transformer 27 and the lead 31 from the whole of the secondary are connected to contacts 18 and 21' respectively. In the position of the springs shown in the drawing the portlon of the transformer secondary winding is associated with the, switchin device and the receiver TR through an obvious 'circult. Upon the operation of contact spring 18 and the simultaneous closure of contact springs 21 and 20 when the wiper 11 engages the contact 13, the circuit which includes lead 29 connected in the middle por tion of the secondary winding of the transformer is opened and the otherhalf portion of the secondary coil added in the new operating circuit which now includes lead 31. Through the closure of contact springs 20 and 21, the added portion of the transformer secondary coil together with resistances and 36, etc., multipled to contacts 13', 14', etc., permit the control of the volume input in 11 additional steps by using the resistances, previously used in a similar consecutive order.

With this switching arrangement it is to be noted that the number of. controlling steps to which this arrangement is capable 1. In an intelligence signaling system, the

combination with a radio amplifier circuit, a switching device comprising sets of contacts, a wiper, a shaft for moving said wiper in contacting relation with each of said contacts, resistances connected to one of said sets and multipled to the contacts of the other set, sets of normally open and closed contact springs, a transformer having portions of its output winding connected to said contact springs, and means operated by the switch shaft for actuating said springs for associating portions of the transformer with said resistances for controlling the volume output in the amplifier circuit. I

2. In an intelligence signaling system, a switching device, sets of multipled contacts arranged in a contiguous row, a potenti ometer having tapped off portions connected to said contact sets and in consecutive order relative to each other, a wiper adapted to be moved in contacting relation with the contacts of each of said sets, a set of contact springs, a transformer having tapped 01f portions connected to said springs, an amplifier tube, and a camming member for actuating said springs for associating the tapped off portions of the transformer through said tube with the tapped off portions of the potentiometer, the potentiometer being effective to control the volume output tacts is effective to associate said potentiometer through said tube with different sections of said transformer.

4, In an intelligence signaling system, the combination with an amplifier circuit, a switching device comprising sets of contacts, a potentiometer having tapped off portions connected to one set, and multipled to the other set, a wiper movable in contacting relation with each of said contacts, a transformer having portions of its output winding normally inefi'ective with respect to said circuit, means for moving said wiper in contacting relation with the contact of the first set for controlling the volume output portion of the connected portion of said transformer, and means operable upon the movement of the Wiper toward the first contact ofthe second set to render the entire transformer winding effective with respect to said circuit.

" In witness whereof, wje hereunto subscribe our names this 17th day of December, A. D..'

JOHN J. KUHN.

WALTER L. BETTS. 

